Plant Growth Promoting Endophytic Bacteria Bacillus australimaris BLR41 and Enterobacter kobei BLR45 Enhance the Growth of Medicinal Plant Barleria lupulina Lindl.

Abstract

A total of 50 root colonising bacterial endophytes were identified from a medicinal plant in this investigation (Barleria lupulina), and characterized based on morphologically selected isolates, BLR41 were Gram-negative motile, rod-shaped and BLR45 was Gram-positive, rod-shaped, and light yellow in color. The BLR41 isolate was motile and the BLR45 was positive for indole. The strains BLR41 and BLR45 were positive for citrate, amylase, protease, and lipase. Among all the isolates, BLR41 and BLR45 exhibited higher enzymatic test positive in citrate, amylase lipase, and protease. Furthermore, PGP efficacy as maximum production of zinc in BLR41 isolate and phosphate solubilization in BLR45. Solubilization of the highest zinc (2.80 μg/mL) was obtained by the isolate BLR41, followed by BLR23 and then BLR35. The highest level of phosphate (2.60 μg/mL) was recorded with the BLR45, followed by the BLR07 and BLR18. A consortium of bacterial strains performed better results than individual inoculation. The isolate BLR41 and BLR45 were identified as Bacillus australimaris and Enterobacter kobei following the 16S rRNA sequencing. Among all, seed germination was induced by 93% in consortium BLR41+BLR45, compared to control (T1). An increase in the shoot length by 30% was recorded with the treatment of BLR41+BRL45, BLR41 increase (54%), and BLR45 (35%), respectively. On the other hand, the consortium of mixed cultures, BLR41+BLR45, showed an increased fresh and the weight of dry 65% and 58%. The findings of this study indicate that the consortium of B. australimaris BLR41 and E. kobei BLR45 significantly enhances plant growth in the Pot experiment by zinc and phosphate solubilization properties.